In machine tool operations, settlement tanks containing filters are widely used to separate machine tool chips and other contaminants, referred to as swarf, from coolant so that clean coolant may be returned to the machine tools for reuse. Generally, such tanks are set below elevation such that sluiceways, likewise located below elevation, convey the contaminated liquid and machining chips to the settlement tank. The chips settle to the bottom of the tank and a dragout conveyor system is employed to convey the chips and swarf from the tank for removal, conventionally up a ramp located at one end of the tank. Filters are employed in the tank to separate the smaller chips and other contaminants from the coolant. While there are many different types of filters and arrangements thereof used for this purpose, one well known and commercially successful system manufactured and sold by the assignee hereof, Henry Filters, Inc. This system uses one or more horizontally disposed filter drums located adjacent the bottom of the tank. A suction is provided to the interior of the filter drum to pull coolant through the filter element. Filter cake, comprised of small chips and other contaminants, is thus formed on the outside of the drum surface. The drum is periodic indexed to enable a doctor blade to shave off a portion of the accumulated filter cake, which drops to the bottom of the tank for removal by the dragout conveyor.
In the example of a filtration system discussed above, a clean coolant is also provided in the tank for receiving the clean coolant filtrate. Although many types of centrifugal pumps are used, such as horizontal split case, end suction, and self-priming types, one embodiment of such a filtration system uses one or more vertical turbine-type pumps. These pumps are disposed in the clean coolant tank for applying suction to the interior of the filter drum(s), as well as for supplying clean coolant to a header for return to the machine tools. More particularly, these vertical turbine pumps each typically comprise an elongated casing connected at its lower end with one or more impeller stage(s) for pumping clean coolant filtrate upwardly through the elongated casing. The impeller stages of each pump are driven by an electric motor mounted at the top of the casing above the liquid level in the tank. The motor drives the impellers by a central drive shaft which extends the length of the casing through multiple bearing assemblies supported the casing. The lower end of the pump is received in a receptor ring located to enable the pump suction to connect through a suction chamber to the interior of the filter drum(s). The outlet for each vertical turbine pump is located above the coolant level of the filtration tank and above the tank itself and is connected to a header into which the clean coolant is discharged for return to the machine tools. Such arrangement is generally described and illustrated in Assignee's U.S. Pat. No. 4,507,061, issued Mar. 26, 1985.
From time to time, one or more of these elongated vertical turbine pumps must be removed from the tank for maintenance, including cleaning and/or replacement of bearings and seals as needed, and thereafter reinstalled. This has required disconnection of mechanical piping connections, such as by unbolting, between the pump and header as well as electrical disconnection of the electric pump motor. As will be appreciated, this involves considerable labor and expense. It also involves imposing on the user of the system requirements which greatly add to the cost of the installation. For example, in certain installations, each vertical turbine pump may have a height of 20 feet or more. To remove such pump from an operating position in a tank below working level, sufficient headroom above the filtration tank must be provided to accommodate the entire height of the pump. For example, to enable a vertical turbine pump having a length of 20 feet or more to be lifted substantially vertically from the filtration tank requires headroom above the tank of approximately a like extent. It will be appreciated that these pumps are quite heavy and require for their removal use of an overhead crane or other lifting mechanism. In many installations, there is just simply insufficient headroom or access space above the tank to enable ready and easy removal and reinstallation of the pump.
Moreover, to remove such a vertical turbine pump from an installation and reinstall it, the services of at least three skilled tradesmen are required, a millwright, an electrician and a pipefitter. Particularly, to effect removal, the electric motor must be disconnected, the bolted connections between the pump discharge and header must be removed, and valves must be closed to isolate the suction and discharge sides of the pump. Thereafter, the elongated heavy vertical turbine pump must be lifted from the tank without damaging it or adjacent ancillary equipment.
Additionally, these vertical turbine pumps are quite expensive to manufacture and are usually custom-built to meet individual application needs. They also require lubrication, which frequently necessitates use of costly automatic lubricators, and customarily have multiple bearings and other ancillary equipment necessary to support their elongated drive shafts. Further, the motors require cooling and lubrication and produce substantial noise.
As will be appreciated, it is desirable to eliminate or minimize noise levels as well as to eliminate the requirement for lubrication because periodic greasing requires substantial labor and adherence to maintenance schedules. Automatic greasing equipment, as required in some installations, substantially increases the cost of such installation. Still further, the entire area above the tank is typically misty from the coolant and moist air, driven by the motor fan for cooling purposes, and such moist air inherently dirties the electric motors, thereby increasing the probability of their malfunction. Thus, there has been a need in the industry to provide pumps which may be readily and easily removed and reinstalled in filtration tanks of this type without the foregoing and other attendant problems.
In Applicant's co-pending Patent Application, Ser. No. 144,058, filed Jan. 15, 1988 in the name of Stephen N. McEwen, which is hereby incorporated by reference, an improved pump and apparatus are disclosed which alleviate some of the aforementioned problems. In that application, the apparatus is disclosed for use in the settlement tanks of industrial machine tool coolant filtration systems like those heretofore described. More particularly, the apparatus allows a pump to be readily and easily removed from and reinstalled in a coolant tank without requiring tools to do the job.
This is accomplished by a structure that allows the pump, having an inlet port and also having a discharge head, to be mounted by the inlet port for fluid communication in an inlet receptor mounted on the bottom of the tank. Above the inlet receptor there is provided a housing or discharge receiver which receives the discharge head of the pump.
In this arrangement, upon mounting, the pump head is telescoped into the discharge receiver and the pump head into the inlet receptor to establish flow communication between an inlet source and discharge. While this installation has proven satisfactory and solved the problems associated with prior mounting arrangements, proper alignment between the housing or discharge receiver and inlet port receptor must be maintained as the pump unit contacts the housing in two regions and the receptor in one region. These contact points require exacting machining of the housing and receptor.